Many beverage products are sold to the consuming public in plastic containers such as are shown in U.S. Pat. Nos. 5,005,716 issued to Eberle; 4,108,324 issued to Krishnakumer et al; and 4,134,510 issued to Chang. The design of plastic containers must take into account the container's structural integrity, the manufacturing cost to mass produce the container, and the aesthetic appearance of the container to the eye of the consumer.
A hot-fillable plastic beverage container must be structurally sound to withstand various forces relating to the so-called "hot-fill" process. Moreover, it must withstand rough handling during transportation to the ultimate consumer. A "hot-fill" process is the procedure by which containers are filled with a beverage at a high temperature after which the containers are capped. As the beverage cools within the container, stresses and strains develop in the container due to changes in the volume of the contents. Containers that store products under pressure, such as carbonated beverages, also experience pressure changes due to changes in ambient temperature. A commercially satisfactory container structure must not only withstand these forces from a structural viewpoint, but it must also present an aesthetically pleasing appearance to the ultimate consumer.
The price of many products sold to the consuming public are affected to an extent by the cost of packaging. With plastic beverage containers, the cost of manufacturing a container is affected by the cost of plastic composing the container. Therefore, if the amount of plastic in a container can be reduced, the cost of manufacturing the container can be reduced commensurately. However, in achieving this goal it is known that the thinner the walls and base of the container become, the greater the need to utilize imaginative designs to provide a container that is commercially acceptable.
The desire to decrease the amount of plastics used in a container has resulted in the development of different techniques to design containers that have structural integrity with minimal use of plastic. It is known that shape and location of structural elements such as ribs, hinges, panels, and the like in either the sidewall, or the base, of the container can affect the container's overall structural integrity. While various structural elements molded in the side panel and base structure can afford structural integrity, they must also be visually appealing to the consumer.
The Krishnakumer et al '324 patent illustrates one container base structure design which has various structural elements molded into the base to enhance its structural integrity. In this container, the base has a series of radially extending ribs. The ribs allow the base structure to withstand the various forces applied while minimizing the amount of plastic required.
The Eberle '716 base structure illustrates an alternate design having structural elements designed to enhance the structural integrity of the base. The structure allows the base to withstand the various stresses and strains applied to the container while using only a limited amount of plastic.
The Chang '510 patent utilizes a series of circumferential ribs in combination with radial ribs to provide the desired degree of structural integrity. In Chang, the various ribs are solid, and the radial ribs intersect all of the circumferential ribs.
Although the aforementioned containers and base structures may function satisfactorily for their intended purposes, there is a need for a blow-molded plastic container having a base structure which enhances container structural integrity while requiring a minimum of plastic. The base structure should be capable of accommodating variations in volume of the containers' contents and changes of pressure and temperature. Furthermore, the base structure should be aesthetically pleasing to the eye and should be capable of being manufactured in conventional high speed equipment.